His path to the big leagues blocked by Alex Rodriguez at third, Eric Duncan is moving across the diamond.

The Yankees’ first-round draft pick in 2003 out of Seton Hall Prep will start next season playing first base for Triple-A Columbus after playing the position in eight of 23 Arizona Fall League games.

“I’m excited, and hopefully it means they will keep me in the system,” said the left-handed hitting Duncan, who hit .362 (34-for-94) with eight homers and 27 RBIs for Grand Canyon and posted a .423 on-base percentage and slugged at a .734 clip, the second highest in AFL history.

“If a position change means staying with the Yankees, I will do it.”

Minor league head Mark Newman said the soon-to-be 21-year-old Duncan’s attitude is the best part of the switch.

“He wants to play for the Yankees and he knows this is his best shot,” Newman said of Duncan, who batted .235 with 19 homers and 61 RBIs for Double-A Trenton and has completely recovered from a late-season beaning.

First baseman Jason Giambi has three more seasons left on his contract and it’s not out of the question he could spend the final two as a DH.

That would leave the position open for Andy Phillips and/or Duncan.

“It’s a lot more difficult than I thought it would be,” Duncan said of first base. “People think it’s easy but there are difficulties, like your footwork.”